The present disclosure generally relates to degradable downhole tools comprising chelating agents, and more specifically, to downhole tools comprising a degradable core and a chelating agent integrated into the downhole tool.
A variety of downhole tools are within a wellbore in connection with producing or reworking a hydrocarbon bearing subterranean formation. The downhole tool may comprise a wellbore zonal isolation device capable of fluidly sealing two sections of the wellbore from one another and maintaining differential pressure (i.e., to isolate one pressure zone from another). The wellbore zonal isolation device may be used in direct contact with the formation face of the wellbore, with casing string, with a screen or wire mesh, and the like.
After the production or reworking operation is complete, the seal formed by the downhole tool must be broken and the tool itself removed from the wellbore. The downhole tool must be removed to allow for production or further operations to proceed without being hindered by the presence of the downhole tool. Removal of the downhole tool(s) is traditionally accomplished by complex retrieval operations involving milling or drilling the downhole tool for mechanical retrieval. In order to facilitate such operations, downhole tools have traditionally been composed of drillable metal materials, such as cast iron, brass, or aluminum. These operations can be costly and time consuming, as they involve introducing a tool string (e.g., a mechanical connection to the surface) into the wellbore, milling or drilling out the downhole tool (e.g., at least breaking the seal), and mechanically retrieving the downhole tool or pieces thereof from the wellbore to bring to the surface.
To reduce the cost and time required to mill or drill a downhole tool from a wellbore for its removal, degradable downhole tools have been developed. The degradable materials that have been proposed for use in forming a downhole tool body are often highly brittle, and can form rock-like solids upon degradation that will cause plugging and stoppage problems in the removal of the downhole tool. Designs and compositions are needed which can help control and direct distribution and production of the byproducts during degradation of a downhole tool and thereby eliminate the propensity for forming plugs.